According to conventional communication network design methods, an optimum design of a network is conducted only when a new network is planned for the first time. During the design process, path and link capacities of a network are designed for a given specific traffic demand. For a given predetermined demand pattern an optimisation of the network design is conducted, and an optimum network minimizing the cost is designed. Afterwards, as the demand pattern changes from the pattern considered during the initial planning phase, it is likely that the efficiency of the network decreases day after day.
In actual telecommunication networks, indeed, the demand pattern varies very frequently, depending upon changes in client subscriptions or changes in traffic load due to the widespreading of new communication services or the introduction of new techniques.
It follows that, in a conventional network, forecast of the demand is hardly possible. Moreover, in multimedia networks of recent years, demand forecast has become more and more difficult.
Currently, the re-design of computer networks, particularly wide area networks, is a complex procedure requiring specialist trained staff. For a nation-wide network, it may take a specialist several weeks to design and simulate an alternative network architecture.
Very often, as the traffic demand increases in correspondence of a particular path or node of a network, a network administrator/operator intervenes simply adding new apparatuses, in order to solve the problem very rapidly. As a consequence the network configuration, as well as the architecture of single nodes, grows in an irregular, confused and very expensive way.
In U.S. Pat. No. 6,223,220 a method of designing a computer network is disclosed making use of an object-based computer representation which allows on-screen linking of a service object, representative of a network service, to site objects representative of physical sites on a wide-area network. The user specifies expected traffic demands between the sites, and an algorithm calculates a physical connectivity map representative of proposed hardware circuits linking physical sites.
The method disclosed in U.S. Pat. No. 6,223,220 analyses the network under known traffic conditions, for determining a network configuration which is optimised for those particular conditions. The network optimisation obtained is therefore strictly connected to a particular traffic condition, representative of a past traffic flow, and does not derive from a forecast of possible future traffic flows on the network.
The Applicant has tackled the problem of designing or optimising a transport network, or even a single network node, in order to satisfy an estimated future traffic demand on the network, with particular attention to realization and reorganization costs. To this purpose a network design and analysis method allowing to evaluate the flow's cost for different network structures is described.
In the following the term “flow” is intended as the allocation, on a transport network system, of an amount of structured bandwidth.
The Applicant observes that one of the main goals when a telecommunication network has to be planned or optimised, is to understand which is the best topology to adopt in order to satisfy the traffic demand and, preferably, to save money.
The Applicant is of the opinion that, since one would hardly know how the traffic demand will evolve in a network, it would be useful to a network administrator/designer to have a methodology able to show, for different network topologies, the probability to satisfy client's needs.
In view of the above, it is an object of the invention to provide a network design and analysis method and device allowing to evaluate the flow's cost for different network topologies, allowing to understand which is the best configuration or evolution for the network under study.